Radiation-Sensitive Novel Polymeric Resist Materials: Iterative Synthesis and Their EUV Fragmentation Studies

Abstract

Polymerization of (4-(methacryloyloxy)phenyl)dimethylsulfoniumtriflate (MAPDST), as a key monomer containing the radiation sensitive sulfonium functionality, with various other monomers such as methyl methacrylate (MMA), 4-carboxy styrene (STYCOOH), N-vinyl carbazole (NVK) in different molar ratios via free-radical polymerization method is described. This methodology led to the development of a small chemical library of six different radiation sensitive polymers for lithography applications. Fourier transform infrared (FT-IR) and nuclear magnetic resonance (NMR) spectroscopy identified the reaction products as MAPDST homopolymer and MAPDST-MMA, MAPDST-STYCOOH, MAPDST-NVK copolymers. Molecular weights were obtained from gel permeation chromatography and the decomposition temperature (Td) values were determined using thermogravimetric analysis (TGA). The effect of extreme ultraviolet (EUV) irradiation on a thin poly(MAPDST) film was investigated using monochromatic synchrotron excitation. These new polymeric materials were also exposed to electron-beam lithography (EBL) and extreme ultraviolet lithography (EUVL) to achieve 20-nm line patterns.

Performance evaluation of nonchemically amplified negative tone photoresists for e-beam and EUV lithography

“…This result contrasted with the MAPDST homopolymer where new functionalities were needed to incorporate in the deconvolution to obtain a right fit after irradiation. 16 The C 1s XPS results match the QMS ones showing that an MAPDST-MMA copolymer may have a higher stability under 103.5 eV SR radiation excitation.…”

“…One of them is the C 5 H þ 9 fragment coincident with the CF þ 3 ion. In our previous publication, 16 it was found that in the case of the MAPDST homopolymer, SO þ 2 and SO þ intensities increased to reach a maximum and then decreased to zero in a few minutes; the m∕z ¼ 69 increased to a maximum and then decreased to the background level. The new contribution of m∕z ¼ 69 observed corresponds to the desorption of CF þ 3 ions produced by 103.5 eV photon excitation.…”

“…The resistance to radiation of the MAPDST-MMA copolymer contrasted with the photofragmentation dynamic of the MAPDST homopolymer. 16 Only 1 min of irradiation of the MAPDST homopolymer at 103.5 eV led almost to the disappearance of the COO signal intensity together with a strong decrease in the CF 3 signal. Additionally, no detection of both signal contributions was observed at 5 min of irradiation.…”

“…[12][13][14][15][16] The resist, poly(MAPDST-co-MMA), was synthesized using azobisisobutyronitrile (AIBN) initiated free radical cross-polymerization between MAPDST and MMA (1∶1 molar feed ratio) at 60°C under a dry nitrogen atmosphere for two days. The molecular weight (M w ) of this copolymer was calculated to be 17.7 × 10 3 by gel permeation chromatography (GPC).…”

“…The new contribution of m∕z ¼ 69 observed corresponds to the desorption of CF þ 3 ions produced by 103.5 eV photon excitation. The results showed that irradiation of the MAPDST homopolymer films produced a fast desorption process where a maximum in the QMS signal intensity is reached between 10 and 15 s. 16 On the contrary, excitation at 103.5 eV of MAPDST-MMA copolymer films yielded a lower QMS signals and the maximum of the intensity is reached at longer times (∼100 s, see inset of Fig. 8).…”